jump hook working, but asm bad?

src/client/component/gsc/script_extension.cpp

@@ -89,7 +89,7 @@ namespace gsc
 			}
 		}
 
-		void vm_call_builtin_function_internal(builtin_function func)
+		void vm_call_builtin_function_internal(int specific_function_id)
 		{
 			const auto function_id = get_function_id();
 			const auto custom = functions.contains(static_cast<std::uint16_t>(function_id));
@@ -99,6 +99,7 @@ namespace gsc
 				return;
 			}
 
+			builtin_function func = func_table[specific_function_id];
 			if (func == nullptr)
 			{
 				scr_error(utils::string::va("builtin function \"%s\" doesn't exist", gsc_ctx->func_name(function_id).data()), true);
@@ -110,8 +111,13 @@ namespace gsc
 
 		void vm_call_builtin_function_stub(utils::hook::assembler& a)
 		{
+			a.mov(rax, qword_ptr(0x6B22918_b)); // 7
+			a.mov(qword_ptr(0x6B183D0_b), rax); // 7
+			a.lea(eax, dword_ptr(rcx, -1)); // 3
+			a.mov(qword_ptr(0x6B22908_b), rsi); // 7
+
 			a.pushad64();
-			a.mov(rbx, qword_ptr(rdx, rax, 3));
+			a.mov(rcx, rax); // TODO: pass builtin_function or id, but is this the right ID???
 			a.call_aligned(vm_call_builtin_function_internal); // call with builtin_function
 			a.popad64();
 
@@ -348,8 +354,8 @@ namespace gsc
 			utils::hook::set<uint32_t>(0xC0E5CE_b + 3,
 				static_cast<uint32_t>(reverse_b((&func_table))));
 			*/
-			utils::hook::nop(0xC0E5CE_b, 12);
-			utils::hook::jump(0xC0E5CE_b, utils::hook::assemble(vm_call_builtin_function_stub), true);
+			utils::hook::nop(0xC0E5BD_b, 24); // nop everything from the lea instruction to the jmp
+			utils::hook::far_jump<0x140000000>(0xC0E5BD_b, utils::hook::assemble(vm_call_builtin_function_stub));
 
 			utils::hook::inject(0xBFD5A1_b + 3, &func_table);
 			utils::hook::set<uint32_t>(0xBFD595_b + 2, sizeof(func_table));

src/common/utils/hook.cpp

@@ -15,6 +15,13 @@
 #undef min
 #endif
 
+Mem seg_ptr(const SReg& segment, const uint64_t off)
+{
+	auto mem = ptr_abs(off);
+	mem.setSegment(segment);
+	return mem;
+}
+
 namespace utils::hook
 {
 	namespace

src/common/utils/hook.hpp

@@ -1,11 +1,14 @@
 #pragma once
 #include "signature.hpp"
+#include "memory.hpp"
 
 #include <asmjit/core/jitruntime.h>
 #include <asmjit/x86/x86assembler.h>
 
 using namespace asmjit::x86;
 
+Mem seg_ptr(const SReg& segment, const uint64_t off);
+
 namespace utils::hook
 {
 	namespace detail
@@ -214,4 +217,52 @@ namespace utils::hook
 	{
 		return static_cast<T(*)(Args ...)>(func)(args...);
 	}
+
+	template <size_t Base>
+	void* allocate_far_jump()
+	{
+		constexpr auto alloc_size = 0x1000;
+		constexpr auto far_jmp_size = 0xC;
+
+		const auto alloc_jump_table = []
+		{
+			return reinterpret_cast<char*>(
+				memory::allocate_near(Base, alloc_size, PAGE_EXECUTE_READWRITE));
+		};
+
+		static auto jump_table = alloc_jump_table();
+		static auto current_pos = jump_table;
+
+		if (current_pos + far_jmp_size >= jump_table + alloc_size)
+		{
+			jump_table = alloc_jump_table();
+			current_pos = jump_table;
+		}
+
+		const auto ptr = current_pos;
+		current_pos += far_jmp_size;
+		return ptr;
+	}
+
+	template <size_t Base, typename T>
+	void* create_far_jump(const T dest)
+	{
+		static std::unordered_map<void*, void*> allocated_jumps;
+		if (const auto iter = allocated_jumps.find(reinterpret_cast<void*>(dest)); iter != allocated_jumps.end())
+		{
+			return iter->second;
+		}
+
+		const auto pos = allocate_far_jump<Base>();
+		jump(pos, dest, true);
+		allocated_jumps.insert(std::make_pair(dest, pos));
+		return pos;
+	}
+
+	template <size_t Base, typename T>
+	void far_jump(const size_t address, const T dest)
+	{
+		const auto pos = create_far_jump<Base>(dest);
+		jump(address, pos, false);
+	}
 }

src/common/utils/memory.cpp

@@ -166,6 +166,33 @@ namespace utils
 		return false;
 	}
 
+	void* memory::allocate_near(const size_t address, const size_t size, const std::uint32_t protect)
+	{
+		SYSTEM_INFO system_info{};
+		GetSystemInfo(&system_info);
+
+		const auto page_size = system_info.dwPageSize;
+		const auto aligned_size = size + (~size & (page_size - 1));
+		auto current_address = address;
+
+		while (true)
+		{
+			current_address -= page_size;
+
+			if (current_address <= reinterpret_cast<size_t>(system_info.lpMinimumApplicationAddress))
+			{
+				return nullptr;
+			}
+
+			const auto result = VirtualAlloc(reinterpret_cast<void*>(current_address), aligned_size, MEM_RESERVE | MEM_COMMIT, protect);
+			if (result != nullptr)
+			{
+				std::memset(result, 0, aligned_size);
+				return result;
+			}
+		}
+	}
+
 	memory::allocator* memory::get_allocator()
 	{
 		return &memory::mem_allocator_;

src/common/utils/memory.hpp

@@ -69,6 +69,8 @@ namespace utils
 		static bool is_bad_code_ptr(const void* ptr);
 		static bool is_rdata_ptr(void* ptr);
 
+		static void* allocate_near(const size_t address, const size_t size, const std::uint32_t protect);
+
 		static allocator* get_allocator();
 
 	private: